1. Field of the Invention
The present invention relates to a data transmission/reception method in Near Field Communications (NFC). More particularly, the present invention to a method for improving data throughput between devices.
2. Description of the Related Art
Near Field Communications (NFC) are used for communications between devices that are spaced from each other typically within about 10 cm. In NFC protocol stacks, the NFCIP-1 standard is used on physical layers of ISO 14443. In NFCIP-1, the devices used for the NFC (or NFCIP-1 devices) may operate in an Active mode or a Passive mode. An NFCIP-1 device in a transmission mode is referred to as an initiator and an NFCIP-1 device in a reception mode is referred to as a target.
In the Passive mode, an NFCIP-1 device does not have its own power source that is required for modulation of its own Radio Frequency (RF) field and thus cannot generate a request message by itself. In the Passive mode, a communication is started by the initiator at all times. In other words, once the initiator in Active mode sends a request message through the RF field, the target in a Passive mode drives a receiver circuit with the power source provided through the RF field. If the initiator does not have transmission data, the initiator periodically transmits a symmetry (SYMM) frame to at least one target. In response to receiving the SYMM frame or an Information (I) frame from the initiator, the target sends back to the initiator the received frame having inserted its own data therein. Thus, the throughput, i.e., data transfer rate, of data transmitted from the target depends on the frequency of the I frame or the SYMM frame received from the initiator.
Moreover, in a current Logical Link Control Protocol (LLCP) version, the initiator has to wait a period of time for reception of a response frame after transmitting a request frame. Due to such a wait, data transfer may be delayed by the response waiting time (RWT). In this mechanism, a unidirectional data transfer from the target inevitably relies on a frequency used for SYMM frame transmission from the initiator to the target.
As a result of the RWT discussed above, when the amount of data to be transmitted between NFC devices increases, a data transfer rate between the NFC devices decreases due to unnecessary idle time or waiting time.
To solve those problems, there is a need for a fundamental method for improving the data transfer rate between NFC devices.